Where to store your MS Access databases
Problem overwriting MS Access Database
 

When your website is initially set up on the server, a directory named "db" is created. This directory has special permissions pre-set that allows data to be written to a file in this directory. This directory is also protected from outside read access on the server level to prevent unauthorized download of your database.

Access databases should be placed in the "db" directory.

If you choose to have an access database in a directory other than "db", you can change the permissions for this directory from the Web Based FTP utility in the Control Panel. Under most scenarios, this directory should be set to "M" (Modify).

When a MicroSoft Access database is in use, the server locks it to prevent the file from being deleted or modified.

A script that is working correctly will lock and unlock a database in less than a second. If, however, your scripts are not closing the database connection after a database query, the database will remain locked. There is a 5 minute timeout set on the server, which will eventually release the database connection, and allow you to overwrite the file, but if you have more that a few users per hour on your website, your database will likely always be in use. You will need to review your scripts and make sure that there is always a close connection string after every open connection string.